Reaction Products of o-(2, 4-Dimethylbenzoyl)benzoic Acid with Polyphosphoric Acid

Abstract

The reaction of o-(2, 4-dimethylbenzoyl)benzoic acid [1] in polyphosphoric acid at 100-120°C gave 1-methyl-3-[2, 4-dimethy1-10-oxo-9(10H)-anthrylidenemethyl]anthraquinone [3] and 1[2, 4-dimethy1-10-oxo-9(10H)-anthrylidenemethyl]-3-methylanthraquinone 4 along with 1, 3dimethylanthraquinone [2], but gave only [2] at 60-80°C. The structures of [3] and [4]were determined based on their MS, IR, NMR and UV spectra, and their chemical behavior. Mechanisms for the formation of [3] and [4] were discussed.